HV9903 Supertex, Inc., HV9903 Datasheet
HV9903
Related parts for HV9903
HV9903 Summary of contents
Page 1
... The device can be enabled/disabled via the SHDN pin. The HV9903 has an internal oscillator. The oscillator frequency is at fixed frequency of 1.2MHz that allows use of small value inductors. The LED current can be adjusted from 5 to 40mA by an external resistor ...
Page 2
... Conditions V mA ºC mA Unit Conditions =0.2V Rset nA V =0V 1.5KΩ SHDN SET Ω 2. 1.5KΩ SET 1.5KΩ, V < V SET DD OUT R = 4.53KΩ SET R = 1.5KΩ SET 1.13KΩ SET R = 750Ω SET R = 562Ω SET mA/º 15mA LED HV9903 ...
Page 3
... A logic high enables the IC via a soft-start sequence Input voltage supply pin. DD capacitor as close as possible to the device on this pin. 3 HV9903 Unit Conditions SHDN SHDN MHz V = 2 > 33V 562Ω, V OUT SET 2. common practice to use a bypass HV9903 = DD SET Rset ...
Page 4
... OVP SHDN Note: This drawing is a generalized representation of the HV9903. Actual internal circuitry may differ. Operation The HV9903 operates as a boost converter that regulates output current rather than output voltage. To maintain constant output current, LED current is monitored via the LED pin and the boost converter’s PWM duty cycle is adjusted accordingly to maintain the desired current level ...
Page 5
... I LED 10mA/div Open LED Protection Open LED protection is integrated into the HV9903. Without open LED protection, output voltage would climb to destructive levels as the driver attempts to correct for the open LED condition. Should the voltage at the SW pin exceed 33V, the driver latches off and the R ...
Page 6
... SW resistance produces a linear voltage ramp. When the inductor saturates, the rapid rise in current produces a likewise rapid rise in SW voltage. Test using an HV9903 with a low switching frequency. SW Waveform Showing Inductor Saturation V IN ...
Page 7
... Peak current rating is the same as for the inductor. Average current is simply the LED current compatible with the HV9903’s open LED protection, the diode’s reverse voltage rating should be 35V or more. Otherwise, the diode’s voltage rating should be greater than the LED string’ ...
Page 8
... Shutdown PWM R SET Dual-cell Alkaline Operation The HV9903 LED driver may be used in 2-cell alkaline battery applications (1.8V min) by powering the power stage directly from the batteries, while powering the HV9903 from an available 3.3V supply. Supplying the SET power stage directly from the batteries reduces the load on the 3 ...
Page 9
... I LED 20V 25V ground connection SET HV9903 OUT 2 GND SHDN 3 R LED SET Keep ground connection seperate and direct to pin HV9903 C OUT GND R SET HV9903 HV9903 Shutdown 4 Fault R SET SHDN ...
Page 10
... The HV9903’s DFN/MLP package fits in most pad layouts designed for a 6-pin SOT-23. Split Supply Operation The HV9903 LED driver may be used in Split Supply application by powering the power stage directly from the batteries, while powering the HV9903 (V an available regulated supply within 2.6V to 4.6V. ...
Page 11
... Shutdown DD 4 Fault R SET LEDs OUT 4 78.5mA 13.1V 6 111.2mA 19.4V LEDs OUT 4 111.3mA 13.6V 6 166.9mA 19.9V LEDs OUT 154.8 4 40.2mA 13.0V 26.1mA 63.4mA 6 19.4V 41.3mA LEDs OUT 4 77.9mA 12.92V HV9903 HV9903 I LED 15.5mA I LED 22.8mA I LED 16.5mA 16.5mA I LED 16.8mA 04/03/06 ...